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There’s a new technology buzzing around mobile carrier circles called License Assisted Access that promises to make our 4G networks faster by dipping into unlicensed airwaves. Most people have never heard of it, but the Wi-Fi industry sure has and it’s raising some red flags.
LAA, also known as LTE-Unlicensed, would tap are the same frequencies Wi-Fi relies on for to deliver its wireless connections, and Wi-Fi advocates are scared the new 4G will muscle out wireless LANs when pitted head to head. The rules of the unlicensed band dictate all users follow some basic rules to prevent devices from interfering with one another. What it all boils down to is if you detect someone using one frequency channel then you move to another channel.
LAA would act much like a Wi-Fi network, but instead of transmitting a Wi-Fi signal in the 5 GHz band it uses LTE. Carriers then combine these LAA signals with their regular 4G transmissions, creating much fatter data connections for smartphones and tablets. Carriers, however, face the same rules as other unlicensed band users in the band. They have to transmit at low power so LAA is really only good for indoor scenarios, and they also have to play nice with other users – i.e. they can’t drown out your home router. Consequently the same interference detection and channel selection technology built into Wi-Fi access points are built into LAA.
So what’s the problem then? The wireless LAN industry’s big trade group, the Wi-Fi Alliance, worries that that carriers will have an edge in the unlicensed bands because their networks are centrally managed. Wi-Fi networks, on the other had, tend to be a patchwork of access points and routers all operating independently but miraculously managing to cooperate. Introducing a centrally controlled and scheduled LAA network into that mix could mess up that mojo. Says the Alliance:
There is a risk that LAA, and especially pre-standard systems deployed ahead of coexistence work being done in the industry, will negatively impact billions of Wi-Fi users who rely on 5 GHz today for networking and device connectivity. It is generally agreed in principle that fair sharing is required, but there needs to be further work from all parties to address this risk in practice.
Driving metaphors are overused when talking about networking, but here the analogy of a racetrack applies. All race cars might be following the rules, but a group of cars acting as a team could gain an advantage by drafting off one another or forcing competitors into different lanes. The Wi-Fi Alliance says that if the mobile carriers took that capability to the fullest extreme they could effectively turn the unlicensed airwaves into a kind de facto licensed band to the determent of all Wi-Fi users.
We’re still in the early days of LAA testing so there is still time to sort the issue out. And the Wi-Fi Alliance isn’t calling for any drastic measures such as banning LTE from the unlicensed band (it would be a bit hypocritical for it do so). But the trade group does want the mobile industry to slow down commercialization work on the technology until it can get these co-existence issues worked out.
[company]Ericsson[/company], already has a LAA small cell in its product pipeline and is testing the technology with [company]Verizon[/company], [company]SK Telecom[/company] and [company]T-Mobile[/company]. Meanwhile T-Mobile CTO Neville Ray has already committed to using LAA in his networks once the technology matures.